Why are the flange distances of these two valves different?
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This post was last edited by Catalyzing a Grain on 2018-5-26 at 17:47. As the title suggests, why do these two DN40 valves have different flange distances? Has anyone encountered this? How do people handle changing valves when the spacing is different?
If the gap is large, weld a short circuit; if it’s small, adjust the pipeline. If that doesn’t work, order a custom gasket
That can’t be right; they all seem to meet national standards.
It’s best to choose one type of valve; otherwise, you’ll have to redo the piping.
If the diameter is the same, could it be that the pressure is different, or is it due to differences between national standards and American standards? If that’s the case, add a short section
One is API600 or ASE16.34 for cast steel, and one is API602 for forged steel; the standards are different.
To address the issue of uneven spacing between valve connections, welders typically weld short pipes made of the appropriate material, with the right diameter and pressure rating, in order to overcome the insufficient distance
The design standards are different; what does that have to do with the structural length?
We have also encountered this problem; it occurs when different standards are used or when manufacturers do not maintain strict quality control – it’s quite common. Therefore, when purchasing valves, it is essential to clarify the standards to be used as well as the nominal length. Generally, first-class valve manufacturers adopt standard unified specifications when users have no specific requirements regarding the structural length. However, many manufacturers have shortcomings in quality control and standard management; for valves of the same model from different batches produced at different times, their structural length can vary. When purchasing valves, we often overlook this aspect as well. Typical designs only specify requirements such as nominal pressure, diameter, fire and static electricity protection, but not the structural dimensions; nevertheless, we still need to clarify these details during the procurement process. Otherwise, valves from different projects or different batches of the same project will have varying structural dimensions, which will cause significant problems during subsequent replacement and maintenance tasks. The valves mentioned above are DN40, so that’s a bit better; but what if it’s large-diameter valves for the main pipelines? Would fire-based modifications be necessary in such cases? Our current approach is to clarify the structural dimensions with the manufacturer before purchasing the valves, and have the manufacturer provide sales drawings as an attachment to the contract.
The two valves have different lengths; they must be valves that meet different standards.